Tuning device for radio receivers



Feb. 9, 1943- R. MASLLORENS TUNING DEVICE FOR RADIO RECEIVERS Filed Sept. 22, 1941 4 Sheets-Sheet l wamflws llbrens,

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Feb. 9,1943.

R. MASLLORENS TUNING DEVICE FOR RADIO RECEIVERS Filed Sept. 22; 1941 4 Sheets-Sheet 5 Feb. 9, 1943. R. MASLLORENS TUNING bEVIcE FOB RADIO RECEIVERS Filed S ept. 22, 1941 4 SheetsSheet 4 Patented Feb. 9, 1943 UNITED STTE optics Application September 22, 1941, Serial No. 411,899 In Argentina September 6, 1941 4 Claims.

This invention relates to a novel and improved tuning device for short and long wave radio receivers and substantially has for object a novel device of the said kind which owing to its several convenient features of construction and operation offers distinct advantages of the devices of similar kind, heretofore known and used.

The improvement which forms the object of this invention, essentially consists in providing the said tuning device with a novel indicating means, substantially formed by an assembled unit of considerable mechanical amplification, which allows of suitably and speedily locating the short wave stations and obtaining their correct tuning by direct reading of the same on a continuous spiral line of great length, along which moves the end of a pointer of variable length, the said assembled unit being further provided with a connecting device for adjusting the indications of said pointer.

A principal advantage of the improved tuning device in accordance with this invention, consists in that the same permits of directly and distinctly reading each short wave station.

A further advantage of the said tuning device in accordance with this invention consists in that thesame allows of location of each of the short wave stations by its respective order, according to the length of wave thereof andits band width in meters for the entire range of the receiver.

Another feature of the novel tuning device which forms the object of this invention, consists in the arrangement of a perfectly smooth control and in the efiicient method of mounting the several elements of the device, so as to avoid all harmful stresses.

On the other hand, and owing to its particular improved construction, the novel device'in accordance with this invention allows of distributing any desired number of short wave stations in a. convenient and spaced manner, one with regard to another, without the necessity of any considerable increase in the dimensions of the corresponding dial, whereby the location and subsequent exact tuning of the same may suitably be performed, with the degree of selectivity required.

, The novel tuning device which forms the obfrom the following specification and appended drawings.

In order that the invention may be clearly understood and readily'carried into practice, a preferred form of construction of the same has been shown by way of example in the accompanying illustrative drawings, wherein:

Figure 1 shows a front view of the improved station tuning device, constructed in accordance with the invention.

Figure 2 illustrates a transverse section on the line AA of Figure 1.

Figure 3 shows a fragmentary View of a detail, drawn to a considerably enlarged scale, of themeans for rotating and synchronously displacing the pointer.

Figure 4 illustrates a detail of the spring tension device which controls the movements of the said pointer.

Figure 5 is-a fragmentary side elevation of the doors for supporting the frame of the locating means and the fastening bolts of said frame.

Figure (i'illustrates a fragmentary front View of said supporting means,

Figure 7lshows a detail of the jointed connection between the operating button of the tuning device and the movable elements of the same.

Figure 8 isa detail in front elevation of said joint.

Figure 9 shows an'alternate construction of the device'for the rotation and synchronous motion of the pointer.

Figure 10 illustrates a cross section, partially in elevation, of the modification of Figure 9, and

Figure 11 is a partial cross section of the modification of Figure 9 on the line 13-13 of the Figure 10.

In all the said views, similar numbers of reference have been used for indicating like or corresponding parts.

In the embodiment shown, in Figures 1-8 the reference number i indicates a short and long wave radio receiver, provided with a knob 2 or the like, for volume control, and with other knobs 3, l, 5 and. 6, for selectivity control, for controlling the tuning pointer, for the change from short waves to long waves, and for the control of tone, respectively, and with another knob, not shown, connectedto the spindle 65, hereinafter to be described, for correcting the setting of the indications, all these elements being arranged in the usual way on'the front side of the receiver l.

Upon referring to Figures 1 and 2, it will also benoted that at the front side of the receiver I, an 1 opening 1, preferably of circular shape, is provided, which allows. of freely observing the dial of the device. for locating the stations, to

be described later on; while inside of the said receiver a plate condenser 8, of known type is arranged, being preferably mounted in a stationary manner on the base plate of the receiver.

In accordance with this invention and the embodiment shown in Figures 1 to 8, a yoke or bracket piece II is secured by means of screws III, or the like, to the outer side of the front plate 9 of said condenser 8, the central part of the bracket piece being of a convenient arcuate shape as shown in detail in Figure 6, so as to allow of the free passage of the shaft I2 of said condenser; the longitudinal slots of the bracket piece being fastened by means of screws, rivets or similar means |3 to the ends of two arms l4, of suitably curved shape and arranged symmetrically one with regard to the other. Each of said arms I4 is formed at its free end with a forked head piece l5 and through the opposite branches of the same extend the screws I6, or similar means, adjustable as to their spacing, and the free ends I! of which are suitably pointed. Although not shown in the drawing, said screws I6 may be provided, if desired, with locknuts or like devices, for preventing the same from shifting.

With reference to Figures 1, 5 and 6, it will further be seen that the free ends of the adjusting screws l5 act after the manner of a pivot against the opposite edges of a small plate l8, at the front of which and parallel to the same, a second small plate I9 is mounted, held fixedly spaced from the former by means of bushings or the like, connected to said plate by screws 2| or similar fastening means.

The assembled plate unit formed by the pair of plates I8 and I9 and the connecting means 28, forms a rigid frame, at the center of which is suitably journalled a shaft 22, of which one end, conveniently extended beyond and outside of the plate I8, is connected to the shaft |2 of the condenser 8; and also carries a sleeve 23 or the like, provided with screws 24; and to the opposite ends of shaft 22 is secured by means of a screw 25 or the like, a disc 26, provided on its front face, by engraving or printing, in an interchangeable manner, if desired, with the inscriptions or characteristic identifications of the several long wave stations, which, as may be seen in detail in Figures 1 and 2, may be observed through a narrow opening 28 formed at the front part of a plate 29, supported in a fixed position by the front plate l9.

To the shaft 22, at the part situated between the small plates I8 and I9, is keyed a toothed wheel 30 which engages at its bottom with a small pinion 3|, integral with a shaft 32, and which engages at its upper part with a pinion 33, integral with another shaft 34, both shafts 32 and 34 being suitably journalled in the plates l8 and I9 and arranged to project in an outward direction with regard to the plate l9.

By referring to Figures 2, 7 and 8, it will be seen that said shaft 32 is provided at its free end with a rectangular extension 35, adapted to snugly fit within a rectangular slot 36, formed at the end of a small plate 31, curved to the shape of a U, rotatably connected to the shaft 38 of the tuning control knob 4 by means of two pins 39 and 40, arranged in a perpendicular position one with regard to the other, so that said plate 31 will form, with the shafts 39 and 40, a Cardan joint for the transmission of movement between said knob 4 and the pinion 3|. In order to be able to vary the rotational turning rate of said pinion 3|, a second knob 4| or a similar operating means, of larger diameter, may be secured by means of a stud, key or the like, indicated at 42, to said shaft 38, adjacent to the control knob 4, above referred to.

As clearly shown in Figures 2 and 3, a fiat member 43 is secured to the outer face of the front plate l9 of the frame, and from the center of said fiat member 43 extends a cylindrical bushing 44, mounted concentrically on the shaft 34 and formed at its end with a circular flange 45. Into said bushing 44 is threaded another tubular bushing 46, also provided with a circular flange 47. On the bushing 46 is rotatably mounted a disc 48, in a concentric position behind the front opening 1 of the receiver, the disc being retained in position by the pressure exerted thereon by the flanges and 41, already referred to.

Upon examining Figure 1, it will further be seen that the said disc 48 is provided at its bottom and in register with the opening 28 of the fixed plate 29, with another opening 49 through which may be read the names, identifications or characteristics 2'! of the long wave stations, marked on the rotating disc 26. On the front face of the disc 48 is marked, by printing, engraving or other suitable means, a spiral line 58 of suitable pitch, on which are marked, in turn, other lines, inscriptions or references, not shown, which characterize the several short wave stations.

Referring to Figs. 1 to 4, on the free end of the shaft 34 is telescoped a resilient bushing 5|, formed at its end with a yoke 52 wherein is axially journalled the bent end 53 of a rod or wire 54, of which the opposite end 55 is suitably lodged in the edge or rim of the front opening 7 of the receiver,

Through said yoke 52 extends perpendicularly a bar or fixed guide 56, of the shape of a U in cross section, in one of the ends of which is rotatably mounted a small pulley 51. The opposite end of said guide piece 56 is closed by a small s plate 58, formed with a hole 59, within which may freely slide a thin pointer 68; on the said bar or fixed guide piece 56, a rotatable drum 6| is mounted, on the periphery of which is wound a cord or light cable 62, suitably connected, at a point between its ends, to the sliding pointer 60, while the opposite end of the said cable is wound in several turns, after the manner of a reel, in one single layer, around the section of straight bend 53 of the wire 54, above described.

As will be noted by observing Figure 4, in the interior of the rotatable drum 6| is arranged a spiral spring 63, having one of its ends connected to the body part of said drum, while the opposite end is aflixed to the shaft 64 and tends to cause the rotation of the same, the device, as just described, thus forming a spring mechanism which, as will later be seen, acts to constantly urge the pointer 60 in an outward or off direction with regard to the guide piece 56. In order to effect the correct operation of the device, the cable 62 is connected to the pointer 60, so that when said pointer is at its position of maximum advance, the spring 63, by a rotation of the drum 6| in the direction of the arrow in Figure 4, will be submitted to a slight degree of tension.

Finally, with reference to Figure 1 it will be seen that in the interior of the receiver I, a small lever 65 is mounted on spindle 65 to swing when .spindle s is turned by its knob. as

above referred to,th'e opposite armsof zsaidrlever' being. connected by means of'cables B1 and .68, or the'like, to two suitable points-of the disc 48, selected in such a position that they. will allow of said cables being alternately put under tension' when the shaft 65 is rotated in any. con-' venient manner, .and will thus cause a slight angular displacement of said disc.

Upon turning: the. tuning control knob 4, or the knob 44, adjacent thereto, in the direction indicated, for instance, by the arrows in Figures 1 and 2, the shaft 38 of said button will operate, through the Cardan joint 31, the shaft 32 of the pinion 3| which, in turn, will cause the rotation of the toothed wheel 30, whose shaft 22 will act through the sleeve 23, on the shaft I 2 of the variable condenser 8 and cause the rotation of the disc, on which will then be located the several characteristic indicia 21 of the long wave stations which will become clearly visible, at a given instant, through the openings 28'and 49 of the fiat member 29 and of the stationary disc 48, respectively.

The rotation of the toothed wheel 30, in turn, will bring about the rotation of the pinion 33 and of the elements integral therewith, viz: the axle 34, the spring urged bushing 5| with its inte ral yoke 52 and the guide bar 56 with its corresponding pointer 60; during said rotating motion, the cord or cable 62 will be caused to wind on the bent end part 53 of the wire 54, and, in consequence, the opposite end of said cable will unwind from the drum 6l, thereby causing the displacement of the pointer 60 man inward direction, as shown by the arrow in Figure 4, while winding, at the same time, the spring 63. The diameter of the end 53 of the wire 54 has been so selected that at each complete revolution of theaxle 34, the pointer fillwill shift to an extent equal to the pitch of the spiral formed by the line 50, so that'at any moment the free endof said pointer will run exactly along the said line and. will thus successively mark the severa1 short wave stations distributed along the same and thereby allow of conveniently localizing the same.

When it is desired to vary the speed of advance of said pointer 60 inrelation to the angular speed, in order to adjust its movement to the l lines 50 of a spiral of different pitch, it will be sufficient to change in a suitable manner the diameter of the bent end 53 of said wire 54.

It will be evident that during the inward movement-of the pointer 60 and the consequent rotation, of the drum 6| in the direction marked by the arrow of Figure l, the spring 63 will tend to wind on its fixed axle 64, thereby increasing, as before stated, its degree of tension, whereby, during its rotation in the reverse direction, the pointer 60 will be moved in an outward direction, against its tendency to remain stationary.

Under certain conditions it may happen that a true registration in the marking of the different short wave stations indicated on the disc 43 is not secured; for the purpose of overcoming this difficulty, the swingable bar 66 is swung towards one side or the other by rotating its spindle 65, whereby traction will be applied to one of the end cables, for instance, to the cable 61, thereby relieving the opposite cable 68, as shown in Figure 1, whereby the said disc 48 may be turned to desired extent through a certain angle about its central shaft, between the space formed by the plain flanges 45 and 41, and the true. registration between the position: of the end of the pointer 60: and the wavelength of the shortwave station tuned in will be re-established and, in consequence, the position with regard to all the other stations. In order to then obtain a change of station, it will be suflicient to cause therotation of said pointer 60 until obtaining itsregistration with the desired station. During the rotating movements above described, the identifications or characteristics 21, corresponding to the long wave stations, will always remain visible, owing to the ampledimensions of the opening 49 of said disc. In general, this adjusting rotation of the disc 48 will not exceed 40 for extreme cases.

The magnitude of this deviation above referred to is uniform depending on the local conditions and equipment of reception and, in consequence, the adjustment will also be uniform.

Besides the advantages obtained by the arrangement as above described, the novel device in accordance with this invention includes the further feature that the support [4, secured to the front plate 9 of the condenser 8, as well as the action of the screws l6 which support the back plate l8 of the'frame, allow of a small amount of axial play of said frame, parallel to the shaft thereof, so as to compensate for any small lack of adjustment, while preventing, notwithstanding, any rotating displacement of the same, so as to avoid any-tensions or stresses which might arise by a rigid connection between said points 11 without providing for the said play.

On the other hand, the telescopic coupling between the end tongue 35 of the shaft 32 and the member 31 of the Cardan joint allows of a small amount of clearance due to tolerances in the elements of the controlling device, while preventing, notwithstanding, any variation of angular orientation and avoiding thereby an torque or compression stresses.

A similar effect is also secured by the telescopic adjustment between the resilient bushing 5| and the shaft 34 of the pinion 33, and the axial displacement allowed to said shaft 33 and the shaft 32 with regard to the plates l8 and IQ of the frame.

Besides, in view of the said frame being maintained by the brackets I4 at about the same height as the operating pinion, this latter will compensate for the tendency to rotating motion of the unit owing to the weak resistance of the grid, and, in consequence, the said grid will rotate without causing any displacements of the unit.

The considerable extended length of the spiral 50 of the disc 48 permits of the distribution on the same of a large number of short wave stations, conveniently spaced from each other, so that a perfect locating of any one of the same may be performed without need of excessively increasing the dimensions of the disc.

According to the modified construction shown in Figures 9 to 11, the resilient bushing 5 1, within which telescopes the shaft 34 of the pinion 33, is rigidly connected, in this case, to a spindle 69, of which the opposite end is secured to the inside of a casing 10, preferably of cylindrical shape, in which is suitably journalled a small spindle 1|, provided with a gear wheel 12, adapted to pass through a suitable slot formed in the casing and to freely rotate in the interior of the same.

By observing the said Figures 9-11, it will be noted that said gear wheel 12 is permanently in engagement with a fixed pinion '13, forming part of a tubular bushing 14, mounted concentrically on said shaft 69 and bushing being provided at its opposite end with a flat flange 15, formed with notches or slots 16, adapted to slide on studs ll, secured to the front side of the plate 19 of the frame. The shaft H, above described, extends with one of its ends outwardly beyond the casing 76 and is provided with a small pinion 18, permanently in engagement with a rack 19 or the like, formed on one of the sides of the pointer 80, the operation of which is similar to that of the pointer 68 of the embodiment first described.

In this case, the said pointer 89 is conveniently guided in a guide or longitudinal direction by a casing 81, which rotates with spindle 69 and within which guide the pointer may slide freely. In order to prevent this latter device from being seen from the front of the receiver, a small disc or plate 82 is mounted in front of the same, being supported by a bushing or similar means 83 which extends from said casing 8!. It will be understood that when the gear 3i] and pinion 33 are caused to rotate, with their associated elements 34 and 5|, the latter will cause the rotation of the spindle 69 and therewith its casing 10, in either of the directions indicated by the arrows in Figures 9 and 10. During such rotation, the internal gear wheel 12, carried along by the 09s ing 70, will remain in engagement with the fixed pinion l3 and will thus also be compelled to re tate, while its center will simultaneously be displaced along the circumference of a circle, towards one side or the other, as shown by the arrows, and owing to the engagement of the pinion 78 with the rack 19 of the pointer 80, the latter will be caused to advance or recede along its guide 8!, thereby submitting said pointer to a synchronous rotating motion on account of the same being integral with the casing 10. In consequence, the free end of the said pointer will move along the spiral line 50 of the disc 48, with an effect similar to that obtained by the operation of the pointer 66, of the construction first above described.

Owing to the telescopic mounting of the flange 75 of the bushing 14, all the other members associated therewith are also allowed a certain amount of axial, but not angular play, so as to assure a perfect tuning of the station located.

From the foregoing description, the manner of operating the radio receiver in accordance with this invention will have clearly been understood and no further explanations will be required by those skilled in the art.

It will be evident that various modifications of of construction and detail may be introduced without departing from the spirit of this invention, and I consider to be part of my invention such modifications which are comprehended within the scope of the appended claims.

Having now clearly described and ascertained the nature of my said invention and the manner in which the same is to be performed, I declare that what I claim and desire to secure by Letters Patent, is:

1. In a tuning unit for radio receivers, a tuning element comprising a rotatable control shaft, manually actuatable means for rotating said control shaft, an indicating shaft, means for rotatably driving said indicating shaft by said control shaft, a register plate positioned on said indicating shaft and carrying a spiral centered about said indicating shaft and with equally spaced turns ,along which wave length indicia are positioned, a guide sleeve member fixedly carried by said indicating shaft substantially perpendicular thereto and positioned to pass over said register plate, a pointer member carried in said guide sleeve member longitudinally slidable therein, and for movement over said register plate, and means actuatable by rotation of said guide sleeve member about the axis of said indicating shaft for progressively varying the longitudinal position of said pointer member in said guide sleeve member radially with reference to said indicating shaft, said means being adapted to displace said pointer member radially of said spiral on said register plate a distance equal to the space between two successive turns of said spiral for every complete rotation of said pointer member.

2. A tuning unit according to claim 1, said means comprising a fixed spindle mounted coaxially with said indicating shaft, a spring drum carried on said pointer member and containing a coiled cord member, a pulley at the end of said guide member, said cord being mounted to pass from said drum along said guide member and over said pulley and being wound around said spindle, and being attached to a point on said pointer member, and the circumference of said spindle being equal to the radial spacing between two successive turns of said spiral.

3. A tuning unit according to claim 1, said means comprising a rack carried on an edge of said pointer member, an arm member extending radially from said indicating shaft and rotatable therewith, a gear wheel rotatably mounted on said am member eccentrically with reference to said indicating shaft, a toothed Wheel fixedly carried on said indicating shaft and engaging said gear wheel, and a pinion fixedly carried by said gear wheel and mounted to engage said rack.

4. A tuning unit according to claim 1, and adjustable setting means positioned adjacent said register plate and adapted to adjust the angular position of said register plate about said indicating shaft to compensate for variations in the wave length response characteristics of the radio receiver.

RAMON MASLLORENS. 

